Tunable infrared lasers can provide a light source for taking images at different wavelengths. These wavelength-dependent images, known as a spectral cube, can be analyzed to determine chemical properties of a material. In order to capture the images, it is necessary to use a camera that is sensitive to the infrared. For cost, ease of use, and high linear dynamic range considerations, it is often desirable to use a microbolometer focal plane array (FPA) as the camera.
Microbolometers are thermal sensors, meaning that they detect a change in temperature. A photon is detected through the heat it generates when it is absorbed by the microbolometer. This is as opposed to a photodetector, which converts impinging photons into electrons for counting. As described herein, this leads to constraints on the way a thermal imager can be operated in order to acquire accurate data to build a spectral cube.
In order to build a practical spectral imager, it is desired to acquire the spectral cube as quickly as possible.